Title

Author

Degree Type

Date of Award

2016

Degree Name

Master of Science

Department

Civil, Construction, and Environmental Engineering

Major

Civil Engineering (Environmental Engineering)

First Advisor

Johannes (Hans) van Leeuwen

Abstract

With an ever increasing demand for energy and a better awareness of its environmental consequences, renewable fuels have become a desirable solution. The growing industry of second generation biofuels, such as renewable diesel, can further supplement energy needs and decrease reliance on fossil fuels. Lipid-rich biomass is a prime candidate for new drop-in biofuel feedstocks. While it has received only minor attention from researchers, fungi has the potential to become an effective source of biofuel. Due to its high moisture content, fungi is well suited for the process of hydrothermal liquefaction. This thermochemical process uses water under near-supercritical conditions to convert biomass into biocrude oil. The use of water eliminates the need for energy-intensive drying processes needed in pyrolysis or gasification. A 1.5-L pilot-scale continuous-flow hydrothermal liquefaction process was optimized for the conversion of filamentous fungi Rhizopus oligosporus to biocrude.

To increase efficiency of a pilot-scale fungi-to-fuel process, improvements to fungal cultivation methods were studied. Large variation in growth yields have been noted for fungi cultivated in thin stillage, and were presumed to be the result of bacterial contamination. However, it was unknown if variations in growth were due to the quality of the thin stillage, contamination during collection, or contamination during lab procedures. Therefore, a lab-scale study was conducted to determine the source of diminished fungal growth yields, and possible methods to overcome these challenges were studied. Specifically, hydrogen peroxide was employed as a disinfectant for thin stillage, and its effect on fungal yields were observed. Results from lab-scale tests helped inform methods used during pilot-scale cultivation of fungi in a 1600-L bioreactor.